Catching Pokémon of these two types was usually less about capture and more about earning their approval. If you truly won their acceptance, catching them would be easy. Otherwise, even if you beat them to death, they might still refuse to listen to you.
Ralts was a prime example. With a Psychic type's intelligence, a Fairy-type's sensitivity, Feelers that sensed emotions, and the Telepathy Ability, she would never have agreed if she had not truly accepted Xiao Ran, no matter how many Pokéblocks he offered her today.
Simply put, it came down to fate. That was why Xiao Ran flatly refused when Xuan Yuan Nian asked to trade for Ralts after he caught her. The request also upset Ralts, who had not given Xuan Yuan Nian a friendly look since.
Not only had she controlled Ralts with Confusion, but she had also tried to take her away. Ralts promptly put Xuan Yuan Nian on her list of bad women—the kind she absolutely had to stay away from.
Back at the Pokémon Center, they turned in their mission and received 20,000 in cash and 50 points. That haul alone exceeded what the other teams had earned over the past two days combined.
Xiao Ran and the others had nothing else planned, so they treated it as a day off. They would likely soon face the same predicament as the other teams: no E-rank missions available, D-rank missions too dangerous to attempt, and only F- and G-rank missions to pass the time.
Fortunately, with 50 points already secured, they were in no hurry. They took their time getting Ralts a complete physical examination. She was newly caught, after all, and they needed to collect her physical data.
"Her Psychic and Fairy-type affinities are both very high, but her physical condition is poor.